They think: we will flood this space with money, drive out competition, and then jack up the price.
They don't think: if we spend all this money, we will have to get a return...the product is free today, is there enough juice here? What will consumers pay?
Charging money impacts the level of demand, spending money like this is literally putting a noose around your neck with investors.
I remember when I first saw this happen...I literally couldn't believe it, these execs knew the business, they were so smart, well-incentivized...it had to work. It never does, it is horrible to read about because people get canned (less so in this case, this spending was clearly an extension of a prominent exec's social life) but you just see it every time with these "land grab" strategies.
To be clear, the mistake wasn't the strategy, it wasn't being wrong, the mistake was choosing to flamboyantly set fire to billions of dollars for no reason.